The present invention relates to a machine for harvesting forage, comprising in particular a support frame, a cutting mechanism and a treatment device intended to treat the products cut by said cutting mechanism and comprising at least two ribbed rollers which are driven in rotation by transmission means comprising at least one flexible element which collaborates with a driving member and driven members which are mounted on shafts which drive the rotation of the rollers.
A machine such as this makes it possible to cut grass and to treat it immediately after cutting by making it pass between the two rollers with a view to accelerating its drying. During this passage between the rollers, the ribs located on their peripheries compress the grass and break up the protective husks surrounding the stems. The moisture contained in these stems then evaporates far more quickly.
In a known machine of this kind, the two rollers are driven at the same rotational speed by means of transmission chains which pass over sprocket wheels. The ribs of these rollers have to mesh so as to obtain close pinches of the stems to increase the intensity of the treatment.
Nonetheless, defects in the shape of these rollers and the inevitable imperfections in the synchronization between the two rollers lead to jolting and jerking in their drive. This jolting and jerking causes overload into the transmission chains which suffer significant wear. It also causes vibration which is detrimental to the bearing structure and particularly to the guide bearings of the rollers.
It is an object of the present invention to overcome the aforementioned drawbacks of the known machine in a simple way.
To this end, a significant feature of the invention consists in the fact that at least one of the driven members of the transmission means which drive the rollers is mounted on its shaft by means of a freewheel driven in just one direction. An arrangement such as this gives the corresponding roller the ability to adapt to the other roller of its own accord. Their ribs then perform gradual and uniform meshing during rotation. That makes it possible to avoid malfunctions due to the defective shapes and defective synchronization of the rollers.
Such a freewheel may be associated with the driven member of just one roller or with the driven members of each of the two rollers. In the latter case, the rollers may compensate for the defects in shape and synchronization in both directions.
According to another feature of the invention, one of the rollers is driven at a rotational speed higher than the rotational speed of the other rotor. The rollers are then synchronized through contact of their respective ribs rather than simply through the transmission means. The latter can consist of simple elements such as belts and pulleys.